The long range goals of this project are to understand the genetic control and molecular mechanisms of pattern formation during development of a cellular embryo, that of the simple and genetically tractable model metazoan Caenorhabditis elegans, by means of a combined genetic and molecular approach. In genetic screens for patterning mutants we have identified five postzygotically expressed nob genes required for posterior patterning of the embryo; at least two of them appear to interact, and one of these is a homologue of the caudal homeobox gene, which is involved in endodermal and posterior development in several diverse organisms. We have also identified a C. elegans TGF-beta homologue similar to the Drosophila decapentaplegic (dpp) gene product, which acts as a morphogen in specification of the dorsal-ventral patterning of embryonic ectoderm as well as in other patterning processes in diverse organisms. In the next project period, we will proceed with 1) investigation of nob gene functions and their interactions, by cloning and molecular characterization of the nob genes, detailed analysis of the corresponding defective phenotypes, and analysis of expression patterns in wild-type and nob mutant backgrounds; 2) continuation of genetic screens for new nob and other patterning genes; 3) investigation of the function of the dpp homologue in C. elegans, by analysis of its expression pattern, isolation of mutants in which it is altered or lacking, and analysis of mutant phenotypes; and 4) investigation of the components and functions of the germ-line-specific P-granules discovered earlier in our laboratory, whose localization in the first four cleavages is likely to be important in specifying embryonic posterior development and the embryonic germ line. The project title, previously "Immunologic studies of C. elegans Early Development," has been changed to better reflect the goals of this research.